Apparatus for and method of desulphurizing molten iron



1956 L B. GILCREST, SR, ET AL APPARATUS FOR AND METHOD OF DESULPHURIZING MOLTEN IRON 4 Sheets-Sheet 2 Filed Nov. 25, 1955 INVENTORS Z .B-GZZO @555? BIGZ'Z Tes'hJT".

TTORNEY Aug. 14, 1956 L. B. GILCREST, SR, ETA!- 2,758,920

THOD OF DESULPHURIZING mourn: IRON APPARATUS FOR AND ME Sheets-Sheet 3 Filed Nov. 25, 1953 IN VENTOR 5 Z15. @z'lorea g- 14, 1956 1.. B. GILCREST, SR, ETAL 2,758,920

APPARATUS FOR AND METHOD OF DESULPHURIZING MOLTEN IRON Filed Nov. 25. 1955 4. Sheets-Sheet 4 INVENTOR5 -[,.5.@?LZ 71232182".

2 ailcreai} J71 United States Patent APP-KRATUS FOR AND METHOD 0F3ESUL- THURIZING MOLTEN IRON Laurence'B. Gilcrest, Sn, Irondale,=and Laurence B. 'Gilcrest, J12, ColunibiaStation, Ohio Application November 25, 1953,-Serial'No. 394,278 '12 "Claims. (Cl. 75-55) :This invention relates to a novel apparatus and method for the treatment of molten iron with desulphurizing chemicals, particularly molten iron asproduced by blast furnaces and cupolas, either-inthe furnace runners or to the molten iron adjacent the bottommost part of the body of molten iron and through alarge number of small orifices-over a large area to'effect optimum intimate contact between-the desu'lphurizer and the molten iron to obtain amaximum'transfer of sulphur fromthe iron to the desulphurizing chemical.

A furtherobject of the invention is to provide a novel apparatus and method to prevent freezing of the desulphurizer while the apparatus is not in operation.

Another object of the invention is to provide novel means for regulating and controlling 'the rate of flow and the total amount of the desulphurizer fed to the molten iron while maintaining anydesired pressure in the feed of the desulphurizer.

A further object of the invention is to provide novel means for-evacuating and ,purging the apparatus where interruptions-in the operation thereof for a considerable period of timeoccur.

Still a further object-of the invention is .to provide a novel means and method of injecting .the desulphurizing chemical in a'gaseous state'into the bottom of a'body of molten iron over a maximum area to insure maximum contact between the'desulphurizerand the iron.

A further object of the invention is to provide means for maintaining a desulphurizing slag on the surface of the molten iron during the desulph'uriz'ing operation to prevent fuming and to obtain maximum deslilphurizing effect.

Various other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, illustrating presently preferred embodiments thereof, and wherein:

Figure l is a side elevational view illustrating one embodiment of the invention;

Figure 2 is an enlarged vertical sectional view, partly in side elevation, ofa portion of 'the desu'lphurizing apparatus;

Figure 3 is an enlarged vertical sectional view taken substantially along a plane as indicated by the line 33 of Figure .1;

Figure 4 is an enlarged'top plan view, partly in horizontal section, of a portion of the apparatus as illustrated in 'Figure 1;

Figure '5 is an enlarged cross sectional view taken substantially along a-plane as indicatedbythe line 55 of Figure 3;

Figure 6 is a somewhat enlarged horizontal sectional :view taken substantially "along a plane *as indicated by the :line ii-"6 of Figure 3 2,758,920 Patented Aug. 14, 1956 Figure 7 is an'exaggerated -ior magnified fragmentary sectional view of a part of the feed .block illustrated in Figure 6;

Figure 8 is an :enlarged fragmentary sectional view taken substantially along a planeas indicated by the .line 8- 8 of Figure 1;

Figure 94's an enlarged fragmentary vertical sectional view taken substantiallyalong a "plane as indicated by the line 9'9 of Figure 3;

Figure 10 is a fragmentary plan view of-another embodimentof a portion :of the apparatus;

Figure 11 is an enlarged longitudinal sectional view taken substantially alonga plane as indicated by the line 1111 of Figure 10;

Figure 12 is an enlarged cross sectional view taken substantially along a plane as indicated by-the line 1212 of Figure 11, and

Figure 1'3 is an enlarged fragmentary sectional view takensubstantially along a'plane asindicated by' the line 1'313-o'f Figure '12.

Referring more specifically ito the drawings, the desulphurizing apparatus in its entirety is designated generally '15 and includes ra meltingwessel or furnace 1'6-p1'eferab1y comprising'an upright casing'17 supported by a base '18 and having araisedbottom 19-combining with the base to forma bottom chamber 20 containing a heating unit 21,-preferably in the form ofa gas burner. The melting vessel also includes a top wall 22 combining with the bottom 1 to form a melting chamber 23 through which extend a plurality of tubes 24. The ends of the tubes 24 extendthrough and-are secured in the bottom "19 and-top wall "22 for carrying oflthe products of combustionfrom the chamber '20 "to the stack 25, located above the top wall 22, and for'heating the contents of the-chamber 23, in combination with the heat radiated from the'bottom *19. Theehamber 23 is adapted =to contain any suitable desulphurizing chemical, such as causticsoda or caustic ash, preferably up to the "level of line "26 in Figure "2. The casing 17 *hasa hopper-or inlet 27 opening into the chamber '23 and opening outwardly thereof above the level 26 of the desulphuriz'ing chemical.

The melting vessel 16 also includes a separate'chaniber 2-8 mounted externally-on-the casing '*1-7 and in communication therewith through "an opening 29 formed in the wall of the casing "17 above and adjacent its bottom'1'9, so that the auxiliary chamber 28 will likewise contain the desulp'hurizing chemical to approximately the same levl as in the'chaniber'23. A centrifugal pump 30 is mounted in the lower'endofthe chamber 28 aud has the inlet thereof opening into said chamber. The pump 30 "is driven by a motor 31 which is mounted on top of the chamber 28and whichis'connected to the pump'30by a motor s'ha'ft32enclosed in'a housing 33.

A conduit 34 connects with and leads from the outlet of the pump 50 through the 'top wall of thec'hamber .28 and is provided adjacent said top wall with a shutofi valve 35. Beyond and adjacent the shutoif valve 35, .a branch conduit 36'havin'g a shutoff valve '37 is connected to said conduit 34. The conduit 36 is adapted to be connected to any suitable source of air under pressure, for a'purpose'th'at willhereina'fterbe described.

The opposite endof'the conduit 34 is connected'to one .end'ofa housing 38 of a superheater, designated generally 39, and discharges into a relatively large chamber '40 thereof. The chamber 40 is lined with refractory material 41. An armored electric-resistance heating element 42 is dis osed in the chamber 40 for super'heating the conductors 44 which-leadzto andfrom .a suitable's'ource of electriccurrent,- not shown.

A branch conduit 45 has an inlet end connected to and communicating with the conduit 34 adjacent the superheater 39. The other, outlet end of the branch conduit 45 discharges into the chamber 23 above the level 26 of the desulphurizing chemical contained therein. 'The branch conduit 45, adjacent its outlet end, is provided with a valve 46 of a suitable conventional construction, preferably a butterfly type valve or other valve which when in a closed position a slight opening W111 be provided to allow the passage of the liquid chemical therethroughfi Such a minimum flow of the ClGSlllPilllllZlfig chemical is provided to prevent freezing or solidifying thereof in the conduits 34 and 45. The valve 46 is controlled by a suitable electrical control 47 which may be operated from a point remote therefrom for varying the extent of opening and closing of the valve 46. Sa1d remote control valve operator 47 may be mounted on a suitable shelf 48 secured externally to a portion of the casing 17,

A conduit 49 has an inletend secured in the opposite end of the superheater housing 48 which opens into the chamber 40 and said conduit is preferably provided with a conventional shutoff valve 50. The conduit 49, remote from the superheater 39 and spaced from its outlet end,

is provided with a flexible portion 51 which is preferably of woven metallic construction.

A portion of a runner section 52 is illustrated in Figure 1 in cross section having a trough 53 lined with a suitable refractory material 54. A suitable support ng base 55 is disposed along one side of the runner section 52 and provides a support for a stand 56 which is secured to and rises therefrom. A horizontally disposed shaft 57 has its ends journalled in aligned upper bearing portions 58 and 58a of the stand 56. As seen in Figure 8, a worm wheel 59 is fixed to the shaft 57 within the bearing portion 58 and meshes with a worm 60, fixed to a shaft 61. The shaft 61 is iournalled in the bearing portion 58 beneath and transversely of the shaft 57 and has an exposed outer end to which is fixed a handwheel 62 for manually revolving the shaft 61 and the shaft 57. A pair of arms 63 are fixed to and extend laterally from the shaft 57 and are pivotally connected at 64 at their free ends to clevises 65 which are fixed to and rise from a shield 66 which is thus supported normally over a part of the runner section 52. The shield 66 has a recessed bottom the top portion of which is lined with a refractory material 67.

An elongated feed block 68, formed of a refractory material preferably inert to chemical reaction and resistant to mechanical and heat shock, such as Carborundum, is supported by the shield 66 and disposed therebeneath. The feed block is provided with upstanding end posts or risers 69 in each of which a headed bolt 70 is anchored. The bolts 70 extend upwardly through bosses 71 Which depend from the recessed underside of the shield 66 and are provided with nuts 72 which engage the top surface of the shield 66 for supporting the feed block beneath the shield. A center post or riser 73 extends upwardly from the intermediate portion of the feed block 68 and abuts against a depending central boss 74 of the shield 66. The other rigid outlet end 49a of the conduit 49 extends downwardly through the boss 74 and the upper portion of the riser 73 and opens into a restricted lower bore portion 75 of said riser 73. The enlarged upper bore portion 75:: of the riser 73 and the bore portion 74a of the boss 74, through which the conduit. portion 49a loosely extends, contain a packing 76 surrounding said conduit portion. Said packing preferably constitutes a rammed type of carbon refractory. A plate 77 is secured to the top of the shield 66 around the conduit 49a for retaining the packing 76 in the bore portions 74a and 75a and for holding the conduit portion 49a in its position of Figure 5.

The feeder block 68 has a plurality of connected internal channels 78 in communication with one another and with the bore portion 75 for receiving the desulphurizing chemical from the conduit end 49a and for the distribution thereof to all portions of the feeder block. The

bottom portion of the feeder block, beneath said conduit 78, is made porous in any suitable manner by the selection of grain size and bond of refractory or by the inclusion of finely divided combustible material, such as sawdust,

with the refractory material when molded, to form minute apertures 79, as illustrated in Figure 7, for the escape of the desulphurizer from the feeder block 68 in a finely divided state and over the entire area of the feeder block bottom to obtain a maximum dispersion of the desulphurizing chemical into the bottom portion of the runner section 52 when the feeder block is in a lowered operative position therein, as illustrated in Figures 1, 3 and 5. Obviously, by turning the handwheel 62 the feeder block and shield may be raised and lowered relatively to the runner section 52. The flexible conduit portion 51 permits the outlet end 49a to move with the shield and feeder block relatively to the inlet end of the conduit 49.

The chamber 23 is charged with the desulphurizing chemical through'the inlet or hopper 27 and wherein said chemical is heated and melted to a molten state and flows through the opening or openings 29 into the auxiliary chamber 25. With the pump 30 driven by the motor 31 and the valve 35 open and valve 37 closed, the liquid desulphurizer will flow through the conduit 34 into the superheater chamber 40 and with a part of the desulphurizer flowing back through the return branch conduit 45 to the melting vessel chamber 23. The amount of this return flow will be governed by the extent that the valve 46 is opened. The desulphurizing chemical within the chamber 40 will be superheated by the resistance element 42 and converted into a gaseous form from whence it will flow through the conduit 49 into the feeder block 63 and be discharged therefrom with maximum dispersion into the bottommost part of the trough of the runner section 52, containing molten iron to be desulphurized. The amount of pressure by which the gaseous desulphurizer is ejected from the feeder block and which is supplied by the pump 30 may be effectively regulated by the remotely controlled valve actuator 47 by means of which the valve 46 can be opened to different extents to vary the amount of the chemical which will be returned to the melting chamber 23 and accordingly the pressure which will be supplied to the superheater 39 and conduit 49.

The superheater additionally functions to provide a chamber 46 of sufiicient capacity to hold a considerable volume of the gasified desulphurizer for relieving excesslve pressures and shock strains on the feeder block 68 and conduit 49.

At the completion of a desulphurizing operation, durconduit 45. Thereafter, the valve 37 is closed and the apparatus is then ready for use for the next cast or pour of iron, by restarting the motor 31 and reopening the valve 35.

The apparatus 15 utilizing the movable feeder block 68 is primarily adapted for use Where the inclination and drop of the runner 52 is not suflicient to obtain a complete evacuation of the molten iron before the iron can solidify. Furthermore, while the feeder block 68 constitutes a manually inserted embodiment, in plants where only an occasional desulphurizing of the iron is required, a manually supported and inserted feeder block may be utilized in lieu of the more complicated mechanically supportedfeeder block as illustrated in Figure 1.

Where considerable desulphurizing of molten iron is required and where the runner section has a suflicient incline or drop, it is desirableto employ a fixed feed block, as illustrated in Figures '10 to, 13 in ,lieu of the parts 55 to 79, as previously described and as illustrated agzaspzo at the right of Figure 1 and in Figures 3 and 5. Such a fixed feed block is. preferably located in a runner section adjacent the blast furnace and with this arrangement,

as illustrated in Figures to 13, the desulphurizing process may be. more effectively and quickly accomplished and the area and depth of iron may be increased to a maximum point, so. that a thick layer of the desulphurizing slag may be maintained on the molten iron.v Likewise, surges in the flow of the iron may be eliminated. and. a substantially continuous operation of the process obtained.

The parts 16 through 48 of the apparatus, as previously described and as illustrated in Figure 1 are. employed without modification with the layout as illustrated in Figures. 19 to 13, and the outlet conduit 49 is modified only to the extent that its flexible portion 51 may be eliminated and its valve 50, if desired, may be located near the mscharge end 49a of said conduit, as illustrated in Figure 10, rather than adjacent the inlet end thereof. In Figures 10, 11 and 12, the desulphurizing runner section 8t) having a substantial pitch downwardly toward its outlet end, as illustrated in Figure 11, is equipped with a stationary feed block 81 formed in the bottom part thereof. The feed block 81 is seated in a rammed carbon refractory lining 82 of the trough of the runner section and which includes a recessed or grooved bottom portion 83. The outlet end 29a of the conduit 49 extends through a bore 84 of the runner section 80 and discharges into the recessed or grooved surface 83 of the refractory lining 82, located immediately beneath the feed block 81. The bore 84 may be packed around the conduit end 49a with the rammed refractory material 82, held therein by a plug 85, located in the upper end of said bore, and through which the conduit portion 49a extends.

As illustrated in Figures 10 to 13, the. feed block 81 is preferably composed of a plurality of individual blocks 81a of Carborundum or any other suitable refractory material and which blocks are interfitted together, as illustrated in Figures 11, 12 and 13, but not secured by any bonding medium. The end walls or ends and side walls of the individual blocks 81a are ribbed or grooved as seen at 811; in Figure 12 to provide minute channels or passages between the underside and upperside of said blocks through which the asified desulphurizer may pass from the channels or grooves 83 outwardly of the upper surface of the feed block 81, substantially uniformly over the entire area of said feed block for maximum intimate contact with the molten iron contained in the runner section 8%. Obviously, if desired, a plurality of the feed blocks 31 can be provided arranged in spaced end-to-cnd relationship, each of which could be connected by branches of the outlet 49a to the conduit 49, or a single feed block 81 of any desired length may be employed.

Figure 10 illustrates a preferred layout Where the runner section 80 is connected at its upper end to an existing runner system 86, near and downstream of a conventional main skimmer 87, which is located in the runner system 86 adjacent a blast furnace, for example, not shown. The runner section 80 includes a downstream portion 83 which returns to the main runner system 86 and which is inclined downwardly from the runner section 80 in which the feed block 81 is disposed. If iron from a blast furnace, for example, is to be desulphurized, a gate 89 of the desulphurizing runner section 80 is opened and a gate 9% in the main runner section 86 is closed. Otherwise, where no desulphurizing is required, the gate 89 is closed and the gate 90 opened. Assuming that desulphurizing is required and that the gate 90 is closed and the gate 89 opened and the iron flow has been established, the molten iron will flow down the desulphurizing runner section 80 and will be stopped by the gate 91 so that the level of the molten iron will rise in the runner section 80. Assuming that the valve 35 is open and that the motor 31 is operating the pump 3.0, the valve 50 is opened and the. valve 46. is adjusted to a desired setting to establish a desired pressure in. conduits 34, 45 and 49 and in the superheater 39, sntficient to cause a flow of the gasified desulphurizer upwardly through the passages 81b, of the feed block into the bottommost part of the molten iron and throughout the entire area of the feed block for maximum intermingling of the gasified desulphurizer with the iron. As the depth of the iron increases in the runner section the pressure of the gasified desulphurizer in the conduit 49 is increased by a gradual closing of the valve 46 by operation of the remote control unit 47 so that the pressure produced on the liquid desulphurizer by the pump 30 will continue to exceed the reacting pressure of the head of molten iron.

In order to maintain a constant level in the volume of molten iron in the runner section 80, a dam 92, as best seen in Figure 12-, is built up across the discharge branch 93 of the runner section 80, which connects said section to the main runner system 8.6. Said dam being, built up out of the refractory lining 82 of said branch conduit 93. A skimmer 94 is provided in the trough of the branch conduit 93 between the runner section 80 and dam 92, a suflicient distance upstream of the dam to permit ample flow of iron under the skimmer. As seen in Figure 12, the bottom edge of the skimmer is disposed several inches below the level of the upper edge of the dam 92 so that iron cannot flow over the dam after the skimmer 94 is submerged in the iron to a depth of several inches. As the desulphurizing slag has a much lower specific gravity than the molten iron, the slag as it is formed immediately rises to and remains on the surface of the iron and the skimmer 94 will prevent passage of the slag to the dam 92 while allowing a free passage of the iron to and over the dam and into the existing runner section 86, for maintaining a desired level of molten iron in the desulphurizing runner section 80.

The heavy layer of molten slag on the surface of the iron is beneficial in preventing fuming as well as in producing additional desulphurizing of the iron. Only a small volume of the desulphurizer is required and as the desulphurizing operation requires only a limited time, the volume of slag produced at each operation is ordinarily no greater than can be contained in the space provided. However, should excess slag occur small volumes thereof may be skimmed ofi manually by scrapers into a shallow trough 95, leading laterally from the branch conduit 93, upstream of the skimmer 94.

After completion of the desulphurizing operation, the gate 91 is partially raised and a small opening is formed through the clay and sand 96, disposed in the runner section 80 around the gate 91 and by which said gate is sealed in a closed position. This bottom opening, not shown, will allow the iron to drain olf before any of the slag can flow past the gate 91. Accordingly, the molten iron flows through the runner portion 88 back into the main runner system 86, after which the slag is either diverted to a lateral passage 97 of the runner section 88, by the opening of a gate 98 therein, to a small sand basin 99, or may be retained in the runner portion 88 immediately downstream of the gate 91, by damming the runner portion 88 with sand after the molten iron has flowed therethrough, which iron flow is'much more rapid than the subsequent slag flow.

The runner section 80 as illustrated in Figure 11 may be closed at its right-hand end to provide a separate vessel or container and the branch 93 thereof may be omitted. This vessel or runner section, thus separated from the runner system as illustrated in Figure 10, may be charged with molten iron from a transporting ladle and the iron may be desulphurized in the manner as 7 previously described and as illustrated in the drawings, after which the gate 91 is raised to permit the iron to flow therefrom as previously described into a previously emptied ladle. The slag following the iron is diverted into a sand pit, as previously described.

Also, if desired, the superheater may be omitted and the desulphurizing chemical supplied in liquid form to the molten iron through the feed block. The liquid desulphurizer will then be gasified on contact with the ll'OIl.

The waters of crystallization of the desulphurizing chemical are eliminated by the melting of the chemical in the chamber 23 before it is conveyed to the molten iron to thus avoid excessive foaming of the desulphurizer which occurs when the same is used in the crystalline form, and which foaming prevents a maximum contact of the desulphurizing chemical with the molten iron.

In lieu of supplying the conduit system with compressed air through the supply pipe 36, the compressed air may be replaced by a more or less inert gas such as CO or CO2, where it is desirable to continue the purging action of the conduit system while maintaining a body of the desulphurized iron in the runner section or vessel. Thus, the somewhat harmful oxidizing effect of the air passing through the molten iron is eliminated. The gas employed may be supplied to the conduit 36 from any suitable container or containers in which the gas is contained under pressure.

Various other modifications and changes are contemplated and may obviously be resorted to, without departing from the spirit or scope of the invention as hereinafter defined by the appended claims.

We claim as our invention:

1. A desulphurizing apparatus comprising a melting vessel having heating means for melting and liquefying a desulphurizing chemical, a feeder block disposed in a desulphurizing runner section, a conduit leading from said melting vessel to said feeder block, a pump interposed in said conduit adjacent the melting vessel for pumping the desulphurizer under pressure from the melting vessel toward the feeder block, a superheater interposed in said conduit including a relatively large chamber containing heating means for superheating and gasifying the desulphurizer, a return branch conduit connected to said first mentioned conduit adjacent the superheater and between said superheater and melting vessel and having an outlet end opening into an upper portion of the melting vessel, and a valve for regulating the flow of the liquid desulphurizer through said return conduit for varying the pressure of the gasified desulphurizer in the feeder block and a portion of the first mentioned conduit located adjacent thereto, said feeder block having a multiplicity of minute outlet passages opening outwardly thereof over a substantial area of the runner section, containing the feeder'block, and discharging into the bottom portion of said runner section.

2. A desulphurizing apparatus as in claim 1, an air pressure supply conduit provided with a shutoff valve and having an outlet end connected to and communicating with the first mentioned conduit adjacent the melting vessel and pump and between said pump and branch return conduit, a shutofi valve interposed in the first mentioned conduit between the air pressure conduit and pump, the shutoff valve of said air pressure conduit being opened and the last mentioned valve being closed and the operation of the pump being interrupted for purging said first mentioned conduit, the branch return conduit, superheater and feeder block.

3. A desulphurizing apparatus as in claim 2, and a shutofl valve interposed in said first mentioned conduit between the feeder block and superheater for selectively purging a portion of the first mentioned conduit located between the valve thereof and the branch conduit and for purging said branch conduit.

4. An apparatus as in claim 1, said feeder block being elongated in a direction longitudinally of the runner section and constituting a part of the trough bottom of the runner section whereby the gasified desulphurizer is emitted upwardly from the feeder block throughout substantially the entire area thereof into the bottom of the molten iron contained in the runner section for maximum intimate contact between the desulphurizing chemical and the molten iron.

5. A desulphurizing apparatus as in claim 4, said feeder block comprising a plurality of individual block sections disposed in abutting engagement and having minute channels extending from top to bottom of certain of the abutting walls thereof and forming the minute discharge passages through which the gasified desulphurizer is discharged into the molten iron.

6. A desulphurizing apparatus as in claim 1, said feeder block being elongated in a direction longitudinally of the runner section, means swingably supporting said feeder block in said runner section or in an inoperative position above the runner section, said first mentioned conduit having a flexible portion located adjacent said supporting means, and said feeder block including a bottom containing the minute outlet passages thereof.

7. A desulphurizing apparatus as in claim 1, said valve of the return branch conduit having means providing a restricted passage for flow of the liquefied desulphurizer therethrough when the valve is in a fully closed position to prevent solidifying of the liquid desulphurizer in said conduit and in the return branch conduit.

8. A desulphurizing apparatus as in claim 7, and a remote control valve actuating means connected to said valve for regulating the amount of the liquid desulphurizer passing therethrough by variably positioning the valve between a fully closed and fully opened position.

9. The method of desulphurizing molten iron in a runner section comprising heating and liquefying a desulphurizing chemical, conveying the desulphurizing chemical under pressure to the mass of molten iron contained in the runner section, superheating and gasifying the desulphurizing chemcial during its travel to the body of molten iron, discharging the gasified desulphurizer into the bottom of the body of molten iron in finely divided form and over a large area of the molten iron, returning a portion of the liquid desulphurizer to the melting area, and regulating said return of the liquid desulphurizer for varying the pressure of the gasified desulphurizer emitted into the molten iron.

10. The method as defined by claim 9, characterized by the step of purging the desulphurizer by air pressure from the passages thereof to prevent solidifying of the desulphurizer during a transit interruption thereof.

11. A desulphurizing apparatus comprising means for melting and liquefying a desulphurizing chemical, a vessel containing molten iron, a feeder block disposed in said vessel submerged beneath the surface of the molten iron, a conduit leading from said means to said feeder block, means for conveying the desulphurizing chemical in liquid form under pressure from said means to the feeder block, a return branch conduit connected to said first mentioned conduit remote from said means and having an outlet end opening into said means, and a valve regulating the flow of the liquid desulphurizer through the return conduit for varying the pressure of the desulphurizer in the feed block, said feed block having a multiplicity of minute outlet apertures opening outwardly thereof over a substantial area of the molten iron containing vessel and discharging into the bottom portion of the vessel.

12. The method of desulphurizing molten metal comprising heating and liquefying a desulphurizing chemical, conveying thedesulphurizing chemical under pressure to a mass of molten metal, discharging the desulphurizer into the mass of molten metal in a finely divided form, returning a portion of the liquid desulphurizer to the melting area, and regulating the return flow of the liquid desulphurizer for varying the pressure at which the de- 5 sulphurizer is discharged into the molten metal.

10 References Cited in the file of this patent UNITED STATES PATENTS 754,566 Hulin Mar. 15, 1904 1,931,144 Gilbert Oct. 17, 1933 2,678,266 Ziflerer May 11, 1954 

9. THE METHOD OF DESULPHURIZING MOLTEN IRON IN A RUNNER SECTION COMPRISING HEATING AND LIQUEFYING A DESULPHURIZING CHEMICAL, CONVEYING THE DESULPHURIZING CHEMICAL UNDER PRESSURE TO THE MASS OF MOLTEN IRON CONTAINED IN THE RUNNER SECTION, SUPERHEATING AND GASIFYING THE DESULPHURIZING CHEMICAL DURING ITS TRAVEL TO THE BODY OF MOLTEN IRON, DISCHARGING THE GASIFIED DESULPHURIZER INTO THE BOTTOM OF THE BODY OF MOLTEN IRON IN FINELY DIVIDED FORM AND OVER A LARGE AREA OF THE MOLTEN IRON, RETURNING A PORTION OF THE LIQUID DESULPHURIZER TO THE MELTING AREA, AND REGULATING SAID RETURN OF THE LIQUID DESULPHURIZER FOR VARYING THE PRESSURE OF THE GASIFIED DESULPHURIZER EMITTED INTO THE MOLTEN IRON. 